Abstract

In this study, we investigate the effect of an Sb-deficiency on the thermoelectric properties of double-filled n-type skutterudite (In_0.05Yb_0.15Co₄Sb_12-x). Samples were prepared by encapsulated induction melting, consecutive long-time annealing, and finally spark plasma sintering processes. The Sb-deficient sample contained a CoSb₂ secondary phase. Both the double-filled n-type skutterudite pristine and Sb-deficient samples showed metallic behavior in electrical conductivity with increasing temperature. The carrier concentration of the Sb-deficient sample decreased compared with that of the pristine sample. Due to a decrease in carrier concentration, the Sb deficient sample showed decreased electrical conductivity and an increased Seebeck coefficient compared with the conductivity and coefficient of the pristine sample. Furthermore, the Sb deficient sample showed an increase in the power factor (σ·S²); the power factor maximum shifted to athe lower temperature side than ones of the pristine sample. As a result, the Sb-deficient sample represents an improved average figure of merit (ZT) and a ZT_max temperature lower than that of the pristine sample. Therefore, we propose that Sb-deficient double-filled n-type skutterudite thermoelectric material (In_0.05Yb_0.15Co₄Sb_12-x) be used in the 573~673 K temperature range.

• Keywords: Skutterudite, Sb deficiency, Thermoelectric properties